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SCMA codebook for Uplink Rician Fading Channels

IEEE COMMUNICATIONS LETTERS 2023年第2期27卷 527-531页

作者： Lei, Tuofeng Ni, Shuyan Cheng, Naiping Chen, Shimiao Song, Xin Space Engn Univ Dept Elect & Opt Engn Beijing 101416 Peoples R China

In this letter, the codebook design criteria for uplink Rician fading channels are explored. The probability distribution of the weighted sums of the Rician random variables from each frequency resource is derived based on the independent non-central circular complex Gaussian random variable. Then, considering the pairwise error probability, the key performance indicators of multidimensional constellations for uplink Rician channels are explored. A sub-optimal optimization approach is deployed to generate an enhanced codebook for various Rician scenarios. Finally, numerical results are provided to verify the key performance indicators in the uplink Rician fading channels.

关键词： Rician channels Uplink Rayleigh channels NOMA Symbols Signal to noise ratio Euclidean distance sparse code multiple access uplink Rician channel key performance indicators codebook design

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SCMA Joint Coding and Decoding Algorithm Based on code Reliability

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MOBILE NETWORKS & APPLICATIONS 2023年第1期28卷 285-295页

作者： Zhao, Hongwei Wang, Huanzhu Yan, Yue Northwestern Polytech Univ Sch Elect & Informat Xian 710129 Peoples R China

The wide application of the Internet of Things (IoT), large-scale satellite clusters and drone clusters requires multiple access capabilities for massive devices. In order to meet the high-capacity and low-latency access requirements in application scenarios such as the IoT, this paper proposes to apply sparse code multiple access (SCMA) technology to the massive terminal access of the IoT, focusing on the study of SCMA decoding algorithm. Aiming at the high complexity of its traditional decoding algorithm, a decoding algorithm based on codeword reliability is proposed. The algorithm reduces the number of codeword iterations with higher reliability by setting a threshold to reduce the algorithm complexity. The simulation results show that the algorithm reduces the complexity of the algorithm while the loss of bit error rate performance is very small. Then, aiming at the poor bit error rate performance of SCMA technology under the condition of low signal-to-noise ratio, a joint coding and decoding simulation link based on soft input and soft output Turbo code and SCMA technology is proposed. The simulation results prove that Turbo codes can speed up the convergence speed of the decoding algorithm. When the SNR is 4 dB, the bit error rate of the joint system has been reduced to below 10e-3, which has obvious advantages compared with the SCMA system without Turbo coding. Therefore, the two methods proposed in this paper can be used for the high-capacity demand of the IoT communication system.

关键词： Internet of things High capacity sparse code multiple access Decoding algorithm

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Coverage Probability and Area Potential Spectral Efficiency Analysis of 3D Dense SCMA Cellular Networks

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2023年第12期22卷 8891-8903页

作者： Soltanpour, Meysam Zhang, Haixia Ding, Hui Shandong Univ Shandong Key Lab Wireless Commun Technol Jinan 250061 Shandong Peoples R China Shandong Univ Sch Control Sci & Engn Jinan 250061 Shandong Peoples R China Yunnan Dev & Reform Commiss Kunming 650051 Peoples R China

This paper investigates the dense multi-user sparse code multiple access (SCMA) cellular networks, where base stations (BSs) and users are randomly deployed in a 3D space by using stochastic geometry tools. First, a method increasing the dimension of the assignment matrix is presented to provide massive connectivity in each cell. The random pattern of arrangement of non-zero elements access (RPA) policy is utilized to allocate the available SCMA resources. Then the coverage probability is characterized under the nearest-BS (NBS) association mechanism by developing a multi-user connectivity model based on the RPA policy and average connectivity ratio (ACR). A compact closed-form expression of the coverage probability and its approximation are derived by utilizing the Toeplitz matrix and finite sum of power series, respectively. We then extract the area potential spectral efficiency (APSE) based on the coverage probability, and provide new insights into the 3D dense multi-cell SCMA networks. Simulation results confirm the precision of the theoretical results and demonstrate the advantage of the SCMA scheme.

关键词： sparse code multiple access 3D multi-cell networks coverage probability poisson point process stochastic geometry

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Dynamic Spectrum Allocation for mMTC Devices Using SCMA-Q-Learning with ACB Overload Control 20th

Dynamic Spectrum Allocation for mMTC Devices Using SCMA-Q-Le...

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20th Chinese Intelligent Systems Conference

作者： Zhang, Hao Li, Zhenghao Wu, Zeyu State Grid ShanDong Elect Power Res Inst Jinan 250002 Peoples R China Jiangsu Univ Sci & Technol Zhenjiang 212100 Jiangsu Peoples R China

ISBN: (纸本)9789819786565;9789819786541;9789819786534

With the development of 5G technology and wireless networks, the limited spectrum resources and increasing number of Machine-Type Communications (MTC) devices in massive Machine-Type Communications (mMTC) networks have led to the problem of Random access Channel (RACH) congestion. sparse code multiple access (SCMA) is a widely used method for random access (RA), which can effectively improve spectrum utilization efficiency. However, using the SCMA method for RA can result in the codebook collision. This paper presents a SCMA-Q-learning method to deal with Low Earth Orbit (LEO) satellite communication networks congestion. This method allow MTC devices to dynamically select the optimal codebook and time-slot-group based on the constantly changing environment. access Class Barring (ACB) technology is employed in overload control. When the system is overloaded, the ACB factor adjusts its size based on the number of accessed devices. Simulation results show that compared with other existing methods, our method can effectively improve the throughput of the entire system.

关键词： Random access Machine-Type Communications Q-learning sparse code multiple access access class barring

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A Joint Design of SCMA codebook and PTS-Based PAPR Reduction for Downlink OFDM Scheme

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2022年第11期71卷 11936-11948页

作者： Chen, Yen-Ming Wang, Pao-Hung Cheng, Chia-Sheng Ueng, Yeong-Luh Natl Sun Yat sen Univ Inst Commun Engn Kaohsiung 80424 Taiwan Natl Sun Yat sen Univ Dept Elect Engn Kaohsiung 80424 Taiwan Taiwan Semicond Mfg Co Ltd Hsinchu 300096 Taiwan Natl Tsing Hua Univ Inst Commun Engn Hsinchu Taiwan Natl Tsing Hua Univ Dept Elect Engn Hsinchu 300044 Taiwan Natl Tsing Hua Univ Inst Commun Engn Hsinchu 300044 Taiwan

In this paper, a joint design of sparse code multiple access (SCMA) codebook and peak-to-average power ratio (PAPR) reduction based on the partial transmit sequence (PTS) technique is proposed for the downlink orthogonal frequency division multiplexing (OFDM) scheme. A benchmark scheme is firstly devised based on a direct extension of the conventional PTS-based OFDM scheme. Based on the characteristics of the near-optimal SCMA codebook designs reported in our previous work, a PTS-based SCMA-OFDM design is proposed by carefully determining the rotation angles of the SCMA codebooks, according to the adopted signal sub-constellations. A receiver which does not need the side information is further devised. Considering the phase ambiguity issue of the receiver, the PTS angles have been carefully refined. When compared to both the original scheme that does not consider PAPR reduction techniques and the benchmark scheme, the proposed scheme achieves a significantly enhanced PAPR performance with approximately the same error performance. In addition, a comparable PAPR performance, an improved error performance, and a lower computational complexity can be achieved when compared to the clipping-based SCMA-OFDM scheme reported in the previous literature.

关键词： sparse code multiple access SCMA non-orthogonal multiple access peak-to-average power ratio partial transmit sequence

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Joint CRDSA and SCMA for Satellite Internet of Things with codebook Collisions

Joint CRDSA and SCMA for Satellite Internet of Things with C...

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2023 IEEE Globecom Workshops, GC Wkshps 2023

作者： Wang, Yiqun Ding, Xiaojin Zhang, Pengjie Xie, Xuxu Zhang, Gengxin School of Communication and Information Engineering Nanjing University of Posts and Telecommunications Nanjing China

ISBN: (纸本)9798350370218

With the rapid development of satellite IoT networks, massive IoT terminals may simultaneously access the satellites, resulting in an increasing demand for user capacity. sparse code multiple access (SCMA) may increase user capacity and spectrum efficiency, through using sparse coding and multi-dimensional mapping method. However, codebook collisions may occur during the on-going wireless transmissions of IoT terminals, because of frequency drift and clock drift of the crystal used by IoT terminals. Relying on our analysis, codebook collisions may dramatically increase the bit error rate (BER). Thus, we conceive a joint contention resolution diversity slotted Aloha (CRDSA) and SCMA (J-CRDSA-SCMA) scheme, to mitigate the impacts on BER caused by codebook collisions. Moreover, the codebook-collision probability of the conceived J-CRDSA-SCMA scheme is also analyzed. Simulation results show that the conceived J-CRDSA-SCMA scheme can achieve a lower BER than the conventional pure SCMA scheme, demonstrating the superiority of the conceived J-CRDSA-SCMA scheme in terms of avoiding codebook collisions. © 2023 IEEE.

关键词： Bit error rate codebook collision contention resolution diversity slotted Aloha satellite IoT sparse code multiple access

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Low Complexity MPA Based on Dynamic Threshold and Stability Judgment for SCMA

Low Complexity MPA Based on Dynamic Threshold and Stability ...

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IEEE Global Communications Conference (GLOBECOM)

作者： Zhao, Xiaoyan Wang, Cheng Cai, Songsong Wang, Weidong Beijing Univ Posts & Telecommun Sch Elect Engn Beijing Peoples R China

ISBN: (纸本)9781665435406

sparse code multiple access (SCMA) is an up-and-coming non-orthogonal multiple access technology. The message passing algorithm (MPA) is utilized for multi-user signal detection in the SCMA system to achieve a performance close to the maximum a posterior algorithm. However, higher iterations will lead to the higher computational complexity of the MPA. In this paper, a dynamic threshold and stability judgment based MPA scheme (DTS-MPA) is proposed to reduce the computational complexity by simplifying the factor graph and reducing the number of iterations. Firstly, an adaptive dynamic threshold is set to minimize the number of iterations in the different channel state information. Secondly, an additional iteration is proposed to determine whether the variable nodes that meet the dynamic threshold reach stable convergence to improve the decoding reliability. Variable nodes that meet the above conditions will be decoded in advance. Numerical results show that the DTS-MPA can significantly reduce the computational complexity of the MPA and achieve a significant trade-off between bit error rate performance and computational complexity.

关键词： sparse code multiple access message passing algorithm dynamic threshold stability judgment

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Performance of SCMA Systems in Fast-Fading Channels 30

Performance of SCMA Systems in Fast-Fading Channels

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30th IEEE Signal Processing and Communications Applications Conference (SIU)

作者： Tufekci, Tolga Ulgen, Oguz Erkucuk, Serhat Baykas, Tuncer Kadir Has Univ Elekt Muhendisligi Bolumu TR-34083 Istanbul Turkey Siemens San Tic AS Kartal AR GE Merkezi TR-34870 Istanbul Turkey

ISBN: (纸本)9781665450928

In order to satisfy the need for high data rate and high number of users, new generation communication techniques are developed. One of the techniques that may be used in future generation communication networks is sparse code multiple access (SCMA). With this new technique, the aim is to allocate users frequency resources in a non-orthogonal way by using code books. For this new technique, which is has a potential to be used in 5G and beyond communication networks, most researches have focused on flat fading channels and related results have been provided. In this work, different from earlier studies, fast fading channels have been considered for channels varying at different rates, and bit-error performance results have been provided with computer simulations.

关键词： sparse code multiple access SCMA Non-Orthogonal multiple access NOMA 5G

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Active User Detection for Uplink NOMA Communication: Deep Learning Approach 14

Active User Detection for Uplink NOMA Communication: Deep Le...

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14th IEEE International Conference on Wireless Communications and Signal Processing (WCSP)

作者： Yu, Chuanhang Li, Chenglin Wu, Gang Univ Elect Sci & Technol China Natl Key Lab Sci & Technol Commun Chengdu Peoples R China

ISBN: (纸本)9781665450850

Recently, with the rapid increase in the number of internet of things (IoT) devices, wireless communications based on orthogonal multiple access (OMA) are greatly limited by limited spectrum resources and the data conflicts and loss caused by large-scale IoT device. In order to support massive user devices, non-orthogonal multiple access (NOMA) have been suggested. In this paper, we focus on the problem of active user detection (AUD) of NOMA-based systems in IoT scenarios, and propose a long short-term memory (LSTM) based detection algorithm to solve the problems of low accuracy and high complexity of conventional AUD algorithms. The simulation results demonstrate that the proposed AUD algorithm based on LSTM network is superior to the conventional orthogonal matching pursuit (OMP) algorithm and the sparse Bayesian learning (SBL) algorithm in terms of both the error detection rate and the missed detection rate. Moreover, when the pilot scheme is designed for sparse code multiple access (SCMA), these two rates are further reduced compared with traditional pilot scheme. Furthermore, we present a detailed complexity analysis and comparison between conventional and deep learing (DL) AUD algorithm, which show the DL-based method greatly reduces the computational complexity.

关键词： internet of things non-orthogonal multiple access sparse code multiple access active user detection long short-term memory

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SER Performance of SCMA Networks with Randomly Distributed Users

SER Performance of SCMA Networks with Randomly Distributed U...

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IEEE/CIC International Conference on Communications in China (ICCC)

作者： Cheraghy, Maryam Soltanpour, Meysam Shanghai Jiao Tong Univ Dept Elect Engn Shanghai Peoples R China Univ Tabriz Dept Elect & Comp Engn Tabriz Iran

ISBN: (数字)9781665484800

ISBN: (纸本)9781665484800

Considering the performance of the sparse code multiple access (SCMA) network as an effective technique to improve spectral efficiency is essential when the signal to noise ratios (SNRs) of users are entirely different, e.g., in random wireless networks. Hence in this paper, symbol error rate (SER) performance is analyzed where the users are randomly distributed in a circular cell. For this purpose, the analytical expression is derived by joint maximum likelihood (ML) receiver with the help of stochastic geometry tools. Then, an upper-bound approximation of SER is extracted to provide useful insight into the network performance. Analytical and simulation results demonstrate the accuracy of our approach. The results show that increasing the number of users with a fixed-overloading factor improves the network performance, while the path-loss exponent decreases the coding gain.

关键词： sparse code multiple access randomly distributed users symbol error rate maximum likelihood

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